Date: Mon, 25 Jun 2007 20:18:06 -0400
Reply-To: Dennis Haynes <d23haynes57@HOTMAIL.COM>
Sender: Vanagon Mailing List <vanagon@gerry.vanagon.com>
From: Dennis Haynes <d23haynes57@HOTMAIL.COM>
Subject: Re: Gurgling after engine shutoff... normal?
In-Reply-To: <30AC0D46-F702-48A5-B4D6-8CED3CFBFB87@knology.net>
Content-Type: text/plain; charset="us-ascii"
Did you test the pressure cap? Is the system holding pressure?
Many parts of an engine can reach temperatures well above the cooling
system bulk temperature. When the engine is shut down, the cooling system
stops pumping and some of that extra heat goes into it. Without pressure
to keep the coolant in contact with the metal parts, you will get vapor.
Heat a pan on the stove and splash some water drops into it. See what
happens? Same thing in an engine. That is why a properly working cooling
system is so important in a modern vehicle. Also the correct antifreeze
mix and wetting agents to break the surface tension. In Diesels these
bubbles actually erode the side of cylinder sleeves and blocks.
This is also why it is a good idea to let an engine idle down after a long
hard run. Even though the cooling system temperature is rising, the
pistons, valves, inside of the heads, oil, etc. are cooling down.
Dennis
-----Original Message-----
From: Jim Felder [mailto:felder@knology.net]
Sent: Monday, June 25, 2007 6:54 PM
To: Dennis Haynes
Cc: vanagon@GERRY.VANAGON.COM
Subject: Re: Gurgling after engine shutoff... normal?
OK, I went out just now for a further test. Low speed fan works, at
least it comes on when the AC is engaged.
Engine runs normally. Upon shutdown, within 20 seconds or so, small
bubbles enter the reservoir from the small diameter hose that comes
from the rear of the right-side cylinder head. This stops after a
minute or two. There is gurgling in the right head, not in the left.
The air bubbles don't accumulate into any identifiable slug of air.
I let it cool and checked the tank. No air. Where is it going? No
exhaust gas contamination, either.
No leaks to the outside, at least no visible ones. No water in the
oil. No bubbles in the water while running, only after the engine is
turned off.
??
Jim
On Jun 25, 2007, at 3:41 PM, Dennis Haynes wrote:
> Absolutley not normal. System is failing to maintian pressure and
> you have
> the resultant hot spots. That gurgling is the result of boiling.
> Boiling
> means liquid to vapor state changes with the massive, unequal
> cooling. Yes,
> you are destroying gaskets and warping heads. First step is look
> for leaks,
> tahn test or rpealce the pressure cap. If that fails, than look for
> internal
> leaks.
>
> Dennis
>
>
>> From: Jim Felder <felder@KNOLOGY.NET>
>> Reply-To: Jim Felder <felder@KNOLOGY.NET>
>> To: vanagon@GERRY.VANAGON.COM
>> Subject: Gurgling after engine shutoff... normal?
>> Date: Mon, 25 Jun 2007 15:11:42 -0500
>>
>> It's hotter than hell around here, as I imagine it is in much of the
>> hemisphere. I have recently noticed that after I park the car and
>> turn the engine off, after 10 or 20 seconds I hear gurgling from the
>> coolant reservoir. The one time I bothered to look I didn't see much
>> going on except the main tank (which was full) trying to take in
>> water from the expansion tank, which was dry.
>>
>> I added water and still it gurgled, presumable it needed more to
>> "catch up" than what I put in. So, yesterday I added more.
>>
>> It still gurgles. Checked cool, the reservoir is completely full
>> without a bubble. The car doesn't overheat (doesn't even get above
>> the coolant light) except in a long line in direct heat with the AC
>> on, and the coolant light operates as if the system is normal. The
>> recent addition of water was the first time I have added any since
>> January. There is no odor or antifreeze inside or outside the car
>> that I can detect.
>>
>> Is this something that I have just now noticed that's been going on
>> all seventeen years of ownership, and I just never noticed it before?
>> Do other Vanagons gurgle like this?
>>
>> Thanks,
>>
>> Jim
>
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